Bun 1.4 is now available in Vercel Functions
Vercel Functions now support the new Bun 1.4 release, a rewrite of Bun from Zig to Rust, with over 2,900 issues resolved, more than 1,500 additional Node.js compatibility tests passing, and new features and performance improvements.
Bun on Vercel Functions:
Runs on Fluid compute with Active CPU pricing
Supports WebSockets and
Bun.serve()Supports common frameworks such as Next.js, Elysia, and Hono
To update from the previous Bun version, set bunVersion to 1.4.x in vercel.json.
Upgrading is an explicit opt-in because Bun 1.4 has several breaking changes. Review the breaking changes and update your application before upgrading.
Learn more about using Bun on Vercel in the runtime documentation.